Still watching for a potential early-season Atlantic subtropical storm

By: Dr. Jeff Masters , 7:10 PM GMT on May 16, 2009

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The latest 00Z and 12Z runs of the GFS, UKMET, NOGAPS, and ECMWF global dynamical computer models continue to indicate the possibility of an early season subtropical storm forming in the Gulf of Mexico 3 - 7 days from now. A modest area of low shear air is expected to open up between the polar jet stream to the north and the subtropical jet stream to the south, between Cuba and the northern Gulf of Mexico. The models have not been consistent with the timing or the size of this low shear area, and I wouldn't be surprised to see them back off again from this forecast with Sunday's set of runs. Nevertheless, I'll call once again for a 10% chance of development of a subtropical depression in the eastern Gulf of Mexico, 4 - 7 days from now. There isn't much of a disturbance at present to look at--there are some scattered showers between Cuba and Jamaica, but they are under a hefty 30 knots of wind shear. These showers should gradually increase in intensity and areal coverage over the next two days, and phase space diagrams from Florida State University indicate that an extratropical low may form near the western tip of Cuba 2 - 3 days from now. The storm may then gradually transition to a subtropical or tropical system later in the week, if the shear is low enough. Even if the shear is high and the storm remains extratropical, it could be a substantial rain-maker where it comes ashore. The models target the northern Gulf Coast between Louisiana and the Florida Panhandle as the most likely landfall location, but it is too early to place any confidence in this track.

There is also about a 10% chance a subtropical storm may form in the mid-Atlantic a few hundred miles east of Bermuda. There, a large upper-level cold low has cut off from the jet stream, and it may spin in place long enough over the next week to develop a warm core and be classified as a subtropical storm. It is unlikely that a subtropical storm forming that far out in the Atlantic this early in the year would pose a threat to any land areas, with the possible exception of Bermuda.

Climatology of early-season Atlantic tropical cyclones
Tropical storms are uncommon in the Atlantic before June 1, with only 26 named storms on record between 1851 - 2008. Five of these have made it to hurricane strength, and only one--Hurricane Able of 1951--made it to major hurricane status. Last year's Tropical Storm Arthur may be the deadliest May tropical cyclone on record. Though only a 40 mph tropical storm at landfall, Arthur killed five people in Belize and caused $78 million in damage. Three early-season storms have brought hurricane-force winds to land. The March 1908 hurricane swept through the northern Lesser Antilles Islands as a Category 1 or 2 hurricane, destroying at least 24 boats and causing damage to buildings on St. Bartholomew. Hurricane Able of 1951 brought sustained winds of 90 - 95 mph to the northern Bahama Islands, but caused little damage. Hurricane 2 of May 1908 hit North Carolina's Outer Banks as a Category 1 hurricane, but also caused little damage.


Figure 1. Tracking map for the earliest hurricane to make landfall, the March 1908 hurricane in the northern Lesser Antilles Islands.

List of all early season (formed in January - May) Atlantic named storms
May 31, 2008: Tropical Storm Arthur
May 6, 2007: Subtropical Storm Andrea
April 18, 2003: Tropical Storm Ana
April 21, 1992: Subtropical Storm 1
May 6, 1981: Tropical Storm Arlene
January 18, 1978: Subtropical Storm 1
May 21, 1976: Subtropical Storm 1
May 23, 1972: Subtropical Storm Alpha
May 17, 1970: Hurricane Alma (Category 1)
May 28, 1959: Tropical Storm Arlene
February 2, 1953: Tropical Storm Alice
May 25, 1952: Tropical Storm 1
May 15, 1951: Hurricane Able (Category 3)
May 22, 1948: Tropical Storm 1
May 19, 1940: Tropical Storm 1
May 27, 1934: Tropical Storm 1
May 14, 1933: Tropical Storm 1
May 5, 1932: Tropical Storm 1
May 13, 1916: Tropical Storm 1
May 24, 1908: Hurricane 2 (Category 1)
March 6, 1908: Hurricane 1 (Category 2)
May 27, 1890: Tropical Storm 1
May 16, 1889: Hurricane 1 (Category 1)
May 17, 1887: Tropical Storm 2
May 15, 1887: Tropical Storm 1
May 30, 1865: Tropical Storm 1

I'll have an update Sunday.

Jeff Masters

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Quoting TampaSpin:


It is next to impossible for anything to develop with these low of SST's and Shear of over 20kts.....Folks it's just not going to happen....Now could a Sub-Tropical something develop possibly but, nothing truly Tropical in nature.....


I agree with you on the shear aspect, but not completely on the SST's. Water temp is plenty warm to allow for tropical development there, albeit not warm enough for explosive development.
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Quoting TampaSpin:


It is next to impossible for anything to develop with these low of SST's and Shear of over 20kts.....Folks it's just not going to happen....Now could a Sub-Tropical something develop possibly but, nothing truly Tropical in nature.....


I dont see SST's as the issue here, more of a shear problem. Would have to agree subtropical development is much more likely than tropical.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Good morning, just stopping in quickly. Caribbean disturbance still looks rather sheared, so I expect no imminent development. I'll keep an eye on it the next few days, if only for the lack of nothing better to watch.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting CycloneOz:
'mornin' everyone.

Arm soreness from digging 70 holes on Friday is about over. I can type again! :)

This is a very interesting pre-game to the beginning of this year's hurricane season. The ULL spinnin' up and stayin' put...[we've all seen that before...] and the convection in the Carribean. Westerlies still movin' along...

Pretty cool! FL may get another dry day today, but I believe lots of rain is comin' soon.



morning!!!,most of us know this scenerio,wait and see....
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1132. Patrap

GOM IR loop
Member Since: July 3, 2005 Posts: 415 Comments: 125715
Quoting WeatherStudent:
Only shear values at around 50knots for say or stronger would destroy this critter, otherwise watch out for development.


It is next to impossible for anything to develop with these low of SST's and Shear of over 20kts.....Folks it's just not going to happen....Now could a Sub-Tropical something develop possibly but, nothing truly Tropical in nature.....
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Quoting WeatherStudent:
Good morning all! I over-slept. Speak to me y'all, what's the latest info in regards to our system this marvelous morning?


good morning and a marvelous one at that,but dam that FL sun is strong!!!!,hows ft leeezy treating ya???......keep an eye on the cenral GOM area today.....
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1128. Patrap
Member Since: July 3, 2005 Posts: 415 Comments: 125715
1126. Patrap


How to start your own blog, and add blog images and links.
Member Since: July 3, 2005 Posts: 415 Comments: 125715
it may form into T.D status if it gets a LLC, and then quickly die.
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1122. Patrap
Maximum Potential Hurricane Intensity

The maps display potential minimum pressure and maximum winds, calculated according to a method developed by Dr. Kerry Emanuel. Dissipative heating is handled according to a method described in Bister and Emanuel (1998). The maps are based on data from the 00Z global operational analysis from NCEP for the date shown on the plot. The top panel shows the potential minimum central pressure for a hurricane at any given location (in millibars). Only values less than 1000mb are shaded. Cyan squares indicate grid points where the algorithm failed to converge. Also shown are the sea surface temperatures (°C). The bottom panel shows the potential maximum wind speed expressed in terms of the type and severity of storm they would represent (TD = Tropical Depression, TS = Tropical Storm, H1-H5 = Hurricanes of category 1-5 on the Saffir-Simpson scale).

Member Since: July 3, 2005 Posts: 415 Comments: 125715
Yea its trying to form now(ULL)guarantee it!!!
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1119. arasky
This is predicted in the Farmer's Almanac for Florida's long range May-June outlook.
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I think we'll all be watching to the central/eastern GOM area by tomorrow morning....it appears the ULL may be starting to form south of AL/MISS border ou in the GOM:Link

this will be the area to watch,IMO...
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1116. Patrap
Member Since: July 3, 2005 Posts: 415 Comments: 125715
1115. Patrap

SREF Last 4 Cycles
Member Since: July 3, 2005 Posts: 415 Comments: 125715
'mornin' everyone.

Arm soreness from digging 70 holes on Friday is about over. I can type again! :)

This is a very interesting pre-game to the beginning of this year's hurricane season. The ULL spinnin' up and stayin' put...[we've all seen that before...] and the convection in the Carribean. Westerlies still movin' along...

Pretty cool! FL may get another dry day today, but I believe lots of rain is comin' soon.
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Quoting canesrule1:
how do you post an image please tell me thanks.


RobdaHood has a tutorial on his blog :)
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Hmmm in 90 minutes.. I am going to be left alll alone to fend for myself.. SWMBO is gone for a week to Quebec... oh how will I survive all by my little lonesome.. with a full beer fridge and Hockey games.. oh woe is me :)
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how do you post an image please tell me ,thanks.
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1110. Patrap
GFSO last 4 cycles
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Quoting Orcasystems:


I don;t think it stands a chance actually...



The shear will kill anything, or at least stop anything from developing


Yeppers your correct.....
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Quoting stillwaiting:



possibly!!!..or a ULL w/split from the jet over the area and slowly MAY work to the surface IF its over warmer deep water and there's less sheer ...


IMO there are several possible scenarios and that one.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting TampaSpin:


Hey now....LOL....

Orca.....look at my values i put in and let me know if you see something different....but, the values i inputted only comes back with a 3% abover average conditions for development. Thats not much....


I don't think it stands a chance actually...



The shear will kill anything, or at least stop anything from developing
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1105. Patrap
-- EMC Cyclogenesis Tracking Page --

Model Cycle: 2009051706



Multi-Model
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Quoting canesrule1:
I was around for andrea, and i will give you that she was more dried out, but this one is just a low with no convection, but i see what you mean.


Andrea barley had any precipitation on radar, this one has much more. Andrea looked like a spinning version of a partly cloudy day in Florida with wind.
Member Since: July 8, 2005 Posts: 259 Comments: 23015
1102. Patrap
Bermuda Sector,IR loop
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Quoting SevereHurricane:


The Caribbean disturbance is going to get absorbed by the ULL coming in the Gulf.That's where the surface low will likely develop.



possibly!!!..or a ULL w/split from the jet over the area and slowly MAY work to the surface IF its over warmer deep water and there's less sheer ...
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1100. Patrap
Satellite Imagery from the University of Miami
There is no endorsement of NWHHC by the University of Miami. Loops are for informational purposes only. Please refer to local emergency management officials for official information

Caribbean Sector,IR Loop
Member Since: July 3, 2005 Posts: 415 Comments: 125715
Quoting hurricanealley:


Hopefully we can sweep the Blue Jays this week


They will...
Member Since: September 7, 2008 Posts: 17 Comments: 1604
how can you post pictures on the comments, thanks.
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http://images.intellicast.com/WxImages/Satellite/hicbsat.gif
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Quoting SevereHurricane:


lol

GO SOX!


Hopefully we can sweep the Blue Jays this week
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Quoting Orcasystems:


ROFL, I just looked at the standings... most teams can look over their shoulders to see the Rays.


Hey now....LOL....

Orca.....look at my values i put in and let me know if you see something different....but, the values i inputted only comes back with a +3% abover average conditions for development. Thats not much....
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http://www.ssd.noaa.gov/goes/east/natl/wv-l.jpg
Check it out you can see both systems how affected they are with the shear
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Quoting TampaSpin:


Hey, are you looking over your shoulder at the RAYS yet.....there coming!


ROFL, I just looked at the standings... most teams can look over their shoulders to see the Rays.
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12z NAM is running
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Quoting canesrule1:
There is circulation in the mid levels of the atmosphere way south of jamaica in the latest loop
Quoting stormpetrol:
no LLC but a definitive mid level spin removed from the deepest convection.


I would say so myself, but to be honest I'm not that sure.
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Quoting CybrTeddy:


Guess you weren't around for Andrea.
Lol. That was a dried STS, worse than that Extra/Sub Tropical Low in the Atlantic.
I was around for andrea, and i will give you that she was more dried out, but this one is just a low with no convection, but i see what you mean.
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Quoting Orcasystems:


What does your model say... yes or no?


Give me 5 minutes to input the current values...
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Quoting hurricanealley:


Great to see you guys starting to play well


lol

GO SOX!
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting TampaSpin:


Hey, are you looking over your shoulder at the RAYS yet.....there coming!


Great to see you guys starting to play well
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.